Peter,
Sorry, that's not what I meant. I'm not trying to gop the goo to fill a
gap. What I meant was that the sticky goo is providing some
friction/cushion between the caliper puck and the back of the pad such that
the pad does not shift in the caliper. When the goo dries and more or less
loses its stickiness, the pad can then move more freely, resulting in a
clunk when transitioning between forwad and reverse motion. Just a theory
waiting to be slaughtered by a cruel set of facts.
I'm not so certain that calipers in good condition are that cheap or
available, but I'd be happy to be enlightened. In any event, my calipers
look good, with no obvious material loss. My main concern is that this
clunk had a finite beginning. Something has changed. I am continuing to
look for the source...
Thanks for all input,
Jeff
At 2:13 PM -0500 12/1/98, Peter wrote:
> Jeff,
> I win? Cool.
> Seriously. The Permatex goo is meant to dampen the harmonics that cause
> the squeal resulting from a pad vibrating against the caliper casting or
> piston. It is meant to be applied to the back of the pad where it contacts
> the piston. It sounds like you want it to fill a gap between the pad edge
> and the caliper casting. I'm not sure it will do that for very long. I wish
> I had a new(ish) caliper to measure what the clearance is meant to be
> between the pad edge and casting (anyone?). In other applications "the
> current book" is to use the original metal shim on the pad (no goo) and a
> high temp anti-seize type grease on the pad edges.(and slides in other
> cars). But mechanics have been chasing pad squeal remedies for years. I
> guess I'd be a little concerned with the side play. Check for a lot of
> removed rust on the caliper and/or compare another set/brand of pads for
> that long dimension. Also, the hardware is cheap enough, you should
> probably replace it.
> Good luck Peter C
> BTW you should be obsessive about brakes.
>
> At 08:56 PM 11/30/98 -0500, Jeff Boatright wrote:
> >Peter may have it right (thanks for the thought, Peter). The pads do move a
> >bit in the calipers. I put more anti-squeal goo (blue goo from Permatex) on
> >the backs of the pads. The squeal and clunk went away. This is what
> >happened when I first installed the new pads. Maybe what is happening is
> >that the blue goo holds the pads while it's still gooey. When it dries, as
> >it always seems to do, the pads start moving.
> >
> >Should the pads be able to move up and down in the calipers? I noticed that
> >the metal retaining clip arms are not evenly compressed against the pad
> >backing ends. The outermost arms (lowest and highest) press against the
> >pads, but the inner arms don't seems to be touching. This could allow the
> >pads to rotate slightly in the calipers, _maybe_. I guess the pads would
> >have the most motion if the brakes were applied during forward motion,
> >released at stop, and immediately reapplied in backwards motion (like when
> >I park against my brick stops in the garage).
> >
> >Has anyone experienced this? Am I obsessing? (Though the clunk has not been
> >a constant with this car).
>
> Peter Caldwell
> 1 very rough Innocenti
> (the Sprite with an accent)
> among other LBCs and 4WDBCs
> Contact for: The Columbia County Bonspiel
> Curling on 13 sheets @ 5 clubs in WI
> Feb 5 - 7 1999
Jeffrey H. Boatright, PhD
Senior Editor, Molecular Vision
http://www.molvis.org/molvis
Mailto:jboatri@emory.edu
404-778-4113
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